will turnγενήσεται(genēsetai)Verb - Future Indicative Middle - 3rd Person SingularStrong's Greek 1096: A prolongation and middle voice form of a primary verb; to cause to be, i.e. to become, used with great latitude.

toεἰς(eis)PrepositionStrong's Greek 1519: A primary preposition; to or into, of place, time, or purpose; also in adverbial phrases.

That ye shall weep and lament, but the world shall rejoice.--Comp. John 20:11, and Luke 23:27. In the original the contrast between the sorrow of the disciples and the joy of the world is rendered the more striking by the order of the words, "Weep and lament shall ye, but the world shall rejoice." The tears and the scoffs at the cross were the accomplishment of this prophecy.

And ye shall be sorrowful, but your sorrow shall be turned into joy.--The expression is a full one. It is not simply that they shall pass from sorrow to joy, but that the sorrow itself shall become joy. They will rejoice in the presence of the Lord, when after a little while they will see Him and will feel that the separation necessarily went before the union, and that the sorrow was itself a matter of joy because it was the necessary cause of the joy (John 16:7, and John 20:20).

Verse 20. - There is no exact or categoric reply to the very inquiry which he has heard and cited, but there is more of prophecy and help than if he had said, "Tomorrow I die and shall be laid in the grave, and on the third day I shall rise again." He had often said this, and they refused to understand. It was not merely a resurrection of the body, but the glorification in the Father of his entire Personality, for which he wished them to be prepared. A simple restoration like that of Lazarus would not have secured him from the malice of those who sought to put Lazarus also to death. Verily, verily, I say unto you, that weep and lament you shall, and the world shall rejoice. Here is his own account of the effect upon them of that he said, "A little while," and you will behold me, as you think, no more. The world will rejoice, because to some extent it will be the world's doing, and it will fancy for a little while that it has got its way and succeeded excellently well The world will roll a stone to his sepulcher, and make it as sure as they can, sealing the stone and setting a watch. Pharisaism will exult that this demand for a higher righteousness than its own is for ever hushed; Sadduceeism will rejoice that this troublesome witness to unseen and eternal things is silenced; the hierarchy will boast that now no danger prevails of the Romans taking away their place and nation; the world will praise the deed of blood; but all this rejoicing will last "a little while." Christ reaffirms their grief, and even for "a little while" justifies it, so long as they can hear the jubilate of the world over their personal burden of unutterable sorrow. He continues: You shall be sorrowful, but in a little while your sorrow shall be (ἐγένετο εἰς, Acts 4:11; Acts 5:36) turned into joy. Clearly because "you shall see me." It cannot be said that our Lord here positively asserts his resurrection; but when we remember how "the disciples were glad when they saw the Lord," how Mary ran "with great joy to bring his disciples word," we feel that here was the simple solution of the mystery, and that our Lord's intercourse with them in his resurrection-body was the great prelibation of the method of his continuous abiding with them in the power of his Spirit and the glorification of his body - we cannot doubt that this was his meaning and the purpose of the evangelist in recording it.